title: Self-cleaning organic/inorganic photo-sensors.
abstract: We present the fabrication of a multifunctional, hybrid organic-inorganic micropatterned device, which is capable to act as a stable photosensor and, at the same time, displaying inherent superhydrophobic self-cleaning wetting characteristics. In this framework several arrays of epoxy photoresist square micropillars have been fabricated on n-doped crystalline silicon substrates and subsequently coated with a poly(3-hexylthiophene-2,5-diyl) (P3HT) layer, giving rise to an array of organic/inorganic p-n junctions. Their photoconductivity has been measured under a solar light simulator at different illumination intensities. The current-voltage (I-V) curves show high rectifying characteristics, which are found to be directly correlated with the illumination intensity. The photoresponse occurs in extremely short times (within few tens of milliseconds range). The influence of the interpillar distance on the I-V characteristics of the sensors is also discussed. Moreover, the static and dynamic wetting properties of these organic/inorganic photosensors can be easily tuned by changing the pattern geometry. Measured static water contact angles range from 125° to 164°, as the distance between the pillars is increased from 14 to 120 μm while the contact angle hysteresis decreases from 36° down to 2°.
authors.affiliation: Nanophysics, Istituto Italiano di Tecnologia, Via Morego 30, 16163 Genova, Italy. athanasios.milionis@iit.it
authors.forename: Athanasios
authors.initials: A
authors.lastname: Milionis
authors.forename: Roberto
authors.initials: R
authors.lastname: Giannuzzi
authors.forename: Ilker S
authors.initials: IS
authors.lastname: Bayer
authors.forename: Evie L
authors.initials: EL
authors.lastname: Papadopoulou
authors.forename: Roberta
authors.initials: R
authors.lastname: Ruffilli
authors.forename: Michele
authors.initials: M
authors.lastname: Manca
authors.forename: Athanassia
authors.initials: A
authors.lastname: Athanassiou